PYSEC-2026-3405

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Import Source
https://github.com/pypa/advisory-database/blob/main/vulns/vllm/PYSEC-2026-3405.yaml
JSON Data
https://api.osv.dev/v1/vulns/PYSEC-2026-3405
Aliases
Published
2026-07-13T15:46:18Z
Modified
2026-07-13T16:33:32Z
Severity
  • 6.9 (Medium) CVSS_V4 - CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N CVSS Calculator
Summary
vLLM: temperature=NaN and temperature=Infinity bypass validation and propagate to GPU kernels
Details

Summary

All temperature validation gates use comparison operators (<, >), which silently evaluate to False for NaN and for positive Infinity in Python's IEEE 754 float semantics. Both values pass every guard and propagate to GPU sampling kernels, where they produce undefined behavior or CUDA errors that can crash the inference worker. Note: -Infinity is correctly caught.

Root Cause

sampling_params.py:384:

if 0 < self.temperature < _MAX_TEMP:  # NaN → False; +Inf → False

sampling_params.py:462:

if self.temperature < 0.0:            # NaN → False; +Inf → False
    raise VLLMValidationError(...)

No math.isnan() or math.isinf() check exists anywhere in sampling_params.py.

Python semantics (verified): float('nan') < 0.0 → False, float('inf') < 0.0 → False.

Impact

Crash of inference worker on GPU kernel execution with NaN/Inf softmax input, degrading service for all concurrent users.

Remediation

Add math.isfinite(self.temperature) check in _verify_args(). Reject non-finite float values with a 400 error.

Fix

A fix for this vulnerability was merged here: https://github.com/vllm-project/vllm/pull/45116

References

Affected packages

PyPI / vllm

Package

Name
vllm
View open source insights on deps.dev
Purl
pkg:pypi/vllm

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0 Unknown introduced version / All previous versions are affected
Last Affected
0.23.0

Affected versions

0.*
0.0.1
0.1.0
0.1.1
0.1.2
0.1.3
0.1.4
0.1.5
0.1.6
0.1.7
0.2.0
0.2.1
0.2.1.post1
0.2.2
0.2.3
0.2.4
0.2.5
0.2.6
0.2.7
0.3.0
0.3.1
0.3.2
0.3.3
0.4.0
0.4.0.post1
0.4.1
0.4.2
0.4.3
0.5.0
0.5.0.post1
0.5.1
0.5.2
0.5.3
0.5.3.post1
0.5.4
0.5.5
0.6.0
0.6.1
0.6.1.post1
0.6.1.post2
0.6.2
0.6.3
0.6.3.post1
0.6.4
0.6.4.post1
0.6.5
0.6.6
0.6.6.post1
0.7.0
0.7.1
0.7.2
0.7.3
0.8.0
0.8.1
0.8.2
0.8.3
0.8.4
0.8.5
0.8.5.post1
0.9.0
0.9.0.1
0.9.1
0.9.2
0.10.0
0.10.1
0.10.1.1
0.10.2
0.11.0
0.11.1
0.11.2
0.12.0
0.13.0
0.14.0
0.14.1
0.15.0
0.15.1
0.16.0
0.17.0
0.17.1
0.18.0
0.18.1
0.19.0
0.19.1
0.20.0
0.20.1
0.20.2
0.21.0
0.22.0
0.22.1
0.23.0

Database specific

source 
"https://github.com/pypa/advisory-database/blob/main/vulns/vllm/PYSEC-2026-3405.yaml"